The invention relates to a compressor for an exhaust gas turbocharger, in which an exhaust gas turbocharger housing includes a gas intake port which substantially radially encloses a gas inflow area. Disposed in the exhaust gas turbocharger housing is a compressor wheel, which can be driven by an exhaust gas turbine.
For example, from DE 100 52 893 A1 there is known a device for improving the efficiency of fluid flow devices, preferably those installed in motor engines. The fluid flow device is an exhaust gas turbocharger in whose exhaust gas turbocharger housing there is disposed a compressor wheel, which can be driven by an exhaust gas turbine. In the area for the inflow of fresh gas into the compressor, the exhaust gas turbocharger housing includes a gas intake port. In order to improve the efficiency of the exhaust gas turbocharger, the gas intake port and a clean air tube disposed in front of the port in the direction of flow, have shapes optimized for flow, that is, the intake contour consists of substantially smooth and round surfaces.
However, it is disadvantageous in the known surface configuration of the gas inflow contour that, despite the surfaces being favorable to flow, disturbing flow noise can occur, in particular on reaching the pumping limit.
Furthermore, from German Patent Specification DE 196 47 605 C2, from which this invention proceeds, a compressor of an exhaust gas turbocharger is known, which basically has the same design as the compressor from the German Laid-Open Publication DE 100 52 893 A1. Unlike the compressor mentioned in the introduction, the gas intake port from DE 196 47 605 C2 includes a radially running annular gap whose flow cross section can be changed in or opposite to the direction of flow by moving a tube disposed in the annular gap. Through this relatively laborious measure the result is obtained that retaining a desirable expansion of the operating limits of the compressor, i.e., an increase of the pumping limit of the compressor, is possible without disturbing noise.
However, a disadvantage in that described arrangement is the great complexity of the construction which is necessary to reduce the noise emissions.
It is the object of the invention to provide a simple measure with which noise, in particular in the range of the pumping limit, can be reduced or eliminated without, at the same time, accepting loss of efficiency of the exhaust gas turbocharger.
This object is realized by a compressor for an exhaust gas turbocharger in which an exhaust gas turbocharger housing includes a gas intake port which substantially radially encloses a gas inflow area. Disposed in the exhaust gas turbocharger housing is a compressor wheel, which can be driven by an exhaust gas turbine. The compressor wheel bounds the gas inflow area in the gas intake port in the direction of flow of a gas. The gas intake port includes indentations on the side of the inflow area.
Through the arrangement according to the invention, the following three different advantageous effects are achieved.
1. Acoustics:
The flow noise itself in normal operation, and the acoustic effects in the case of pumping, are clearly reduced.
2. Flow:
The oscillations in air mass during pumping are clearly reduced in the inflow area, and the intake flow is clearly made uniform in normal operation.
3. Costs:
The arrangement according to the invention can be integrated into existing technology in a particularly simple manner and large-volume and expensive resonators in the air duct can be eliminated.
The location of the indentations is advantageously in an area which can be machined in a particularly simple manner. In particularly preferred embodiments, the indentations are formed as holes or radially running grooves. Advantageously, the indentations project between 0.5 mm and 5 mm into the gas intake port. The indentations advantageously have a diameter or a width between 0.5 mm and 10 mm. These particularly preferred ranges help achieve the advantages noted above.
An additional improvement of the effect according to the invention is achieved by an arrangement wherein the indentations include a back-cut opposite to the flow direction. The indentations are advantageously arranged so as to be distributed with either a uniform or a non-uniform spacing.
In particularly preferred production processes, the indentations are produced with or without machining.
In an arrangement that can be upgraded in a particularly simple manner, the indentations are disposed in a separate tube, which can be introduced into the gas intake port. The arrangement is also a realization which can be upgraded in a particularly simple manner.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.